1. Technical Field
This invention relates in general to the field of compressors, and more particularly, but not by way of limitation, to systems and methods for utilizing and/or modifying portions of a conventional automobile engine for use as a gas compressor.
2. Background
Gas compressors are used in various applications where either higher pressures or lower volumes of gas are needed, such as, for example, in petroleum refineries, natural gas processing plants, petrochemical and chemical plants, and similar large industrial plants for compressing intermediate and end product gases, and in pipeline transport of purified natural gas from the production site to the consumer. Often, compressors in these environments are driven by a gas turbine which may be fueled by a gas bled from the pipeline, thus, no external power source is necessary.
Pumps for liquid pipelines and compressors for gas pipelines are often located at compressor stations along the pipeline to facilitate the transportation of product through the pipelines. The location of these stations may be defined by the topography of the terrain, the type of product being transported, and/or operational conditions of the network. For example, natural gas, while being transported through a gas pipeline, needs to be constantly pressurized, requiring compressor stations to be located in certain distance intervals along the pipe ranging anywhere from 40 to 100 miles or more. Oftentimes, specially customized turbines, motors, and/or engines are required in each of these compressor stations, which may be in remote locations.
One type of compressor often used along a gas pipeline is a reciprocating compressor. A reciprocating compressor or piston compressor is a positive-displacement compressor that uses pistons driven by a crankshaft to deliver gases at high pressure. The intake gas enters a suction manifold, then flows into the compression cylinder where it is compressed by a piston driven in a reciprocating motion via a crankshaft before being discharged back into the pipeline. Reciprocating compressors can be either stationary or portable, can be single or multi-staged, and can be driven by electric motors or internal combustion engines. Small reciprocating compressors from 5 to 30 horsepower (hp) are commonly seen in automotive applications and are typically limited to intermittent duty. Larger reciprocating compressors, well over 1,000 hp (750 kW) and capable of very high discharge pressures (e.g., >6000 psi or 41.4 MPa), are commonly found in large industrial and petroleum applications.
In the past, these types of large industrial compressors have been utilized for the compression of gas for use in recovery, gathering, transfer, and/or storage of natural gas. There are various potential benefits to using these large industrial compressors including accessibility to the interior areas of the compressor for maintenance purposes such as, for example, removable access panels and/or easily removable major components. Oftentimes, maintenance access options are not available in smaller compressors. However, these large industrial compressors are not practical for field use for various reasons, including, for example, cost, weight, size, and hp requirements.
Various prior art devices currently in use for gas compression include modified devices from other industries. In some devices, industrial compressors, such as industrial horizontal compressors, are converted for use in natural gas compression. One drawback to the use of this type of compressor for natural gas compression is that it requires a specialized manufacturer to manufacture modified parts for conversion to a natural gas compressor. In addition, the extensive modifications also require specially manufactured components for use, maintenance, and repairs, which greatly increases the operating cost of such devices.
In other prior art devices, compressors have been formed utilizing modified automotive engines to provide both power to the device and compression. However, utilization of such mono-block designs to compress natural gas may be considered to involve some operational risks because of the proximity of the cylinders having combustion therein and the cylinders having a flammable material such as natural gas flowing therethrough. One prior art device, as disclosed in U.S. Pat. No. 5,267,843, which is hereby incorporated by reference, attempts to overcome this danger with a complicated venting systems to vent any gas that might build up in the compressor.
Many of the prior art devices for utilizing an internal combustion engine as a compressor contemplate converting an automobile engine having a V-shaped configuration, such as for example, a V-8 engine, into a compressor. However, there are various deficiencies inherent to the V-shaped orientation of the cylinders of, for example, a V-8 engine relative to use as a compressor. One prior art device, as disclosed in U.S. Pat. No. 4,700,663, which is hereby incorporated by reference, attempts to overcome some of these deficiencies by utilizing a modified horizontally opposed engine, such as the Type-1 VOLKSWAGEN internal combustion engine, to form an air compressor.